rear speakers dont work.

how to enable them?

 

Really could be anything. Head unit, amp, speakers themselves, or just a slipped cable from any of these areas.
Use a AA battery connected to a couple of wires and work your way through connectors touching the + and - wires to each. You will hear a crackle noise in teh speaker that confirms the connection. Then just work backwards towards the head unit.

You could be a while getting at all the connectors though!

 

With a 2008 XJ you have a X358 series with an aluminum body .

Suggest posting in that area for people with that design .

In the mean time Blgdave is correct in the use of a 9 volt battery and the scratch test starting with the amplifier connections .

I'll look up a wiring diagram for you stereo system if available . Below :

[url]http://www.jagrepair.com/images/Electrical/XJElectrical/2008%20MY%20XJ%20Electrical%20Guide.pdf /url] See page 154 but your premium system is on page 157

If you need a part one X358 came into the local salvage yard .

 

I would not use a 9v battery. AA battery is just 1.5V and works just fine

Cheers

 

There may be a stereo mode selector not switched correct like say a telephone mode . , That could be easier to check the owners manual then chasing wires .

 

Also rear speakers fade/balanced out option.